<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            box-sizing: border-box;
        }
        #outBox{
            height: 400px;
            width: 600px;
            border: 1px solid #000;
        }
    </style>
</head>
<body>
<div id="outBox">
    <div></div>
</div>
<script>

</script>
</body>
</html>